Frunk Core

这个库是 Frunk 的核心。它应该尽可能简单，只包含泛型编程的基本构建块。

示例

let h = hlist![1, false, 42f32];
let folded = h.foldr(hlist![|acc, i| i + acc,
    |acc, _| if acc > 42f32 { 9000 } else { 0 },
    |acc, f| f + acc],
    1f32);
assert_eq!(folded, 9001);

// Reverse
let h1 = hlist![true, "hi"];
assert_eq!(h1.into_reverse(), hlist!["hi", true]);

// foldr (foldl also available)
let h2 = hlist![1, false, 42f32];
let folded = h2.foldr(
            hlist![|acc, i| i + acc,
                   |acc, _| if acc > 42f32 { 9000 } else { 0 },
                   |acc, f| f + acc],
            1f32
    );
assert_eq!(folded, 9001);

// Mapping over an HList
let h3 = hlist![9000, "joe", 41f32];
let mapped = h3.to_ref().map(hlist![|&n| n + 1,
                              |&s| s,
                              |&f| f + 1f32]);
assert_eq!(mapped, hlist![9001, "joe", 42f32]);

// Plucking a value out by type
let h4 = hlist![1, "hello", true, 42f32];
let (t, remainder): (bool, _) = h4.pluck();
assert!(t);
assert_eq!(remainder, hlist![1, "hello", 42f32]);

// Resculpting an HList
let h5 = hlist![9000, "joe", 41f32, true];
let (reshaped, remainder2): (HList![f32, i32, &str], _) = h5.sculpt();
assert_eq!(reshaped, hlist![41f32, 9000, "joe"]);
assert_eq!(remainder2, hlist![true]);

链接

1. GitHub 上的源代码
2. Crates.io 页面